In recent years, an increased and continuing emphasis has been placed on the recovery of hydrocarbonaceous fluids from substantially non-volatile carbonaceous materials such as oil shale, lignite, coal, industrial and municipal solid wastes and the like, as an alternative to conventional production of petroleum from finite and rapidly depleting and underground sedimentary reservoirs. Previous efforts by both governmental agencies and private industry have demonstrated that these alternative or unconventional carbonaceous material-containing resources can be converted with varying degrees of difficulty into volatile hydrocarbonaceous fluids such as combustible gases, motor fuels, heating and fuel oils and various by-products which have value in the chemical and petrochemical industries. In general, the more attractive of the recovery techniques previously proposed invariably involve heat treatment of the substantially non-volatile carbonaceous material in a manner sufficient to distill or otherwise decompose the solid carbonaceous material into the aforementioned volatile products. These techniques, which can be described in most basic terms as retorting or pyrolysis processes, take on a myriad of forms including batch or continuous schemes utilizing fixed or fluidized beds wherein either a portion of the solid carbonaceous material itself is combusted to supply the pyrolysis heat, or the pyrolysis heat is generated externally and supplied to the process via a gaseous (fluidized gas), liquid or solid heat carrier.
Of all the available materials, coal is considered by many to be one of the best candidates for processing in such a retorting or pyrolysis scheme. When coal is pyrolyzed, usuallly at temperatures of about 800.degree. to 1500.degree. C., the solid coal undergoes destructive pyrolysis and is converted to liquid and light gaseous hydrocarbonaceous fluids with a remainder staying as a char having valuable fuel capabilities.
One problem associated with many coals, particularly western coals, is the presence of significant amounts of water in the coal. Such coals, for example, may contain up to 30 or even 40 percent water. This water may be present as a physical mixture or as chemi-absorbed water. Since this large volume of water is not desired in the pyrolysis, steps must be taken to remove the water prior to the heat treatment. The present invention provides an efficient method of water removal, as well as providing for the recovery of a balance of highly valuable products.